Cubase/Nuendo stuck on "Initializing: All MIDI Inputs"

Cubase and Nuendo cannot launch because the application gets stuck on the loading screen at "Initializing: All MIDI Inputs."

Microsoft recently started the rollout of new MIDI implementation (incl. MIDI 2.0) for Windows 11 24H2 and 25H2: 
Making music with MIDI just got a real boost in Windows 11

Unfortunately, this has led to a series of issues with certain MIDI devices and hardware configurations, where the MIDI services cannot be properly initialized. As a result, applications such as Cubase and Nuendo may become stuck during the initialization process.

Microsoft provides a regularly updated list of known issues and workarounds here: Windows MIDI Services rollout – known issues and workarounds

For now, the easiest solution is to roll back to a previous Windows version by uninstalling the latest update or reverting to an earlier system restore point. You can find detailed instructions on Microsoft’s website:

How to uninstall a Windows Update

System Restore

Otherwise, keep an eye on upcoming Windows updates and make sure your operating system is always up to date, as future updates will address the described issues. 

If you would like direct support from Microsoft or want to share information for further investigation, Pete Brown (Principal Software Engineer in the Windows Developer Platform) has posted details about contact options and known workarounds in our forum: The Microsoft Windows MIDI Services rollout – Important info